A gas turbine engine may be used to power various types of vehicles and systems, such as aircraft engines and auxiliary power units in aircraft. In a typical configuration, the turbines of such engines include rows of stator vanes and rotor blades disposed in an alternating sequence along the axial length of a generally annular hot gas flow path. The rotor blades are mounted at the periphery of one or more rotor disks mounted on a main engine shaft. Hot combustion gases are delivered from an engine combustor to the annular hot gas flow path, thus resulting in rotary driving of the rotor disks and main engine shaft to provide an engine output.
In most gas turbine engine applications, it is desirable to regulate the operating temperature of the engine components in order to prevent overheating and potential mechanical failures attributable thereto. Temperature control of gas turbine engines is complicated by hot gas leaking through gaps in the mainstream flow path, particularly in the areas between the rotating rotor assemblies and the stationary stator assemblies. While the engine stator vanes and rotor blades are specially designed to function in the high temperature environment of the mainstream hot gas flow path, other engine components, such as the rotor disks, are generally not designed to withstand such temperatures. Accordingly, in many gas turbine engines, the volumetric space disposed radially inward to the hot gas flow path may be cooled by air flow bled from a compressor of the gas turbine engine. The cooling of internal engine cavities attempts to maintain the temperatures of rotor disks and other internal engine components at levels that are suitable for their material and stress level.
In many conventional engines, relatively high cooling air flows have been used to obtain satisfactory temperature control of engine components within the cooled internal engine cavity. However, any air used for cooling is not available for use to produce mechanical energy, thus reducing the efficiency of the engine. Additionally, such cooling schemes are complicated by the relatively irregular and unpredictable ingestion of mainstream hot gases from the hot gas flow path into the internal engine cavity. Various attempts to prevent hot gas ingestion between adjacent stator vanes and rotor blades have been proposed, including baffles, flow discouragers, and pocket structures. In the past, these techniques have not been completely effective, or have otherwise required structures of complex shape and/or mounting arrangements at the time of initial engine production.
Accordingly, it is desirable to provide an improved gas turbine engine that reduces or eliminates hot gas ingestion into the internal cavities within the turbine. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.